Communication Control Device Buffer Management for USB Burst Transfer
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Solution Overview
Problem
USB controllers face increased circuit size and higher product costs due to the need for expanded buffer capacity to support burst transfer and independent communication across multiple endpoints, leading to potential flow control issues and decreased transfer rates.
Innovation Solution
A communication control device with dedicated buffers of at least one packet size per endpoint and shared common buffers with capacity equal to the number of packets in a burst transfer, where the first packet is buffered in the dedicated buffer and subsequent packets are buffered in the common buffer, minimizing overall buffer size and ensuring continuous data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacity of the dedicated buffer is increased to support burst transfer, then the buffer capacity is sufficient for continuous data transfer, but the circuit size increases resulting in higher product costs
Solution Approach 1:
The patent merges the buffer capacity requirements by introducing a common buffer that is shared across multiple endpoints. Instead of each endpoint having a dedicated buffer of size packet size × maximum burst length, the system uses a common buffer of size packet size × maximum burst length that serves all endpoints, thereby reducing the total circuit size while maintaining sufficient buffer capacity for burst transfer operations.
Solution Approach 2:
The common buffer is designed to serve multiple endpoints universally. The buffer management device allocates the common buffer to multiple endpoints in a shared manner, allowing any endpoint to use the common buffer when needed. This multi-functional approach reduces the total buffer capacity required compared to having separate dedicated buffers for each endpoint.
2Quantity of substance
If the capacity of the dedicated buffer and common buffer are both set to packet size × maximum burst length, then sufficient buffer capacity is provided, but when burst transfer continues, the common buffer cannot be secured on time for the next burst transfer
Solution Approach 1:
The system performs preliminary buffer allocation for the common buffer before the next burst transfer begins. The buffer management device proactively allocates the common buffer to the endpoint that needs it, ensuring that the buffer is ready in advance. This preliminary action prevents the flow control issue where the common buffer could not be secured on time during continuous burst transfers.
3Productivity
If the dedicated buffer capacity is increased to accommodate continuous burst transfer, then data transfer can proceed without flow control, but the circuit size increases leading to higher costs
Solution Approach 1:
The patent combines the buffer resources by using a common buffer that is shared across multiple endpoints. This merging approach allows the system to maintain high data transfer rates during burst transfer without requiring each endpoint to have a large dedicated buffer, thereby avoiding the increase in circuit size while preserving productivity.
Data Source
AI summary
A communication control device includes reception controllers capable of receiving data in a burst transfer mode in which packets are continuously transferred as one burst. There are dedicated buffers having a capacity of one packet for each of a plurality of endpoints and common buffers shared by the endpoints; a first packet of a burst transfer is stored in the dedicated buffer; and a common buffer is secured at the same time. The dedicated buffers and common buffers are controlled according to a transfer status.